1. Technical Field
The present invention relates to a fluid pressure producing method and a fluid pressure producing device for pressuring a fluid by applying the pressure of a working medium to a double-acting piston and driving a plunger.
2. Description of the Background
Fluid pressure producing devices known in the art pressurize a fluid by applying the pressure of a working medium to a double-acting piston and thus driving a plunger. Such fluid pressure producing devices use the pressure of the working medium to pressurize the fluid. The discharge pressure of the fluid can have large pulsations due to the discharge performance of the working medium pump, response delays of the direction control valve, and compressibility of the working medium and the fluid.
Waterjet technology uses a jet of ultrahigh pressure fluid discharged from a fluid pressure producing device in cutting or other machining processes. The fluid pressure pulsations can cause flow rate pulsations, which can cause a disturbance in the jet. Techniques have thus been developed to control the fluid pressure. One such technique known in the art directly drives a plunger with a servo motor and maintains the constant moving speed of the plunger to shorten the time taken for switching the moving direction of the plunger (Japanese Patent No. 3822362, or hereafter Patent Literature 1).